Precautions for dynamic balance of different types of rotors

1. Balancing of rolling bearing rotors Rotors equipped with rolling bearings should be balanced together with the rolling bearings to eliminate the imbalance caused by the eccentricity of the inner ring of the rolling bearing. The rotors with bearings are generally carried out on the V-shaped support.

2. The balance of the rotor without journals. The rotor without journals must be balanced on the process shaft. Due to the manufacturing error of the process shaft itself: radial and axial runout. The unbalance of the process shaft itself and the diameter that exists when the rotor is matched Directional clearance, so that the rotor will bring inevitable errors when balancing.In order to separate the unbalance caused by the matching error of the process shaft and the part from the unbalance of the neckless rotor, only the unbalance of the rotor is detected on the process shaft, and the balance method of 180° indexing can be used.

3. The balance of the assembly As the assembly is composed of several parts, if the individual parts are not balanced first, then: The assembly cannot be balanced due to the excessive imbalance.Or although it can be balanced to make the assembly reach the specified balance accuracy, but at the actual working speed (4000 ~ 50000r/min), due to the imbalance force of the impeller and the influence of the force couple, the shaft is locally bent and vibrates and cannot work. So. , Each part must be balanced first at a low speed (1～2000 rpm), and the allowable value of balance can be allocated according to the allowable value of unbalance of the assembly.After assembly, it is theoretically believed that although the unbalanced quantity is the vector sum of the unbalanced quantities of each individual piece, a new unbalanced quantity will still appear due to assembly errors and the assembly will not meet the requirements, so the assembly should still be balanced.Generally, the balanced assembly should not be disassembled. If the process requires that it must be disassembled, the relative position of each part should be marked so that when reinstalling, the original relative position can be restored to ensure its overall accuracy.Since the mark is only obviously effective for the radial rotation mark and has no effect on the axial mark, it is still difficult to guarantee the restoration of the original balance accuracy after the assembly is disassembled and reassembled. For example, the rotor assembly that is matched by the shot peening surface, if you want to To reduce the assembly error as little as possible, the locking force must be strictly controlled (for example, the locking force of the inner support type rotor assembly should be recorded, etc.).For some assembly parts (such as shafts with blades), the shaft can be balanced on a balance machine with a static couple separation of the force measurement and the force couple, find the vector direction, and then install the blades and balance them in a targeted manner. Greatly reduce the unbalanced weight and ensure the appearance quality.